Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

Working with XML DocumentsTo be fully accessible, an XML document must be entirely loaded in memory and itsnodes and attributes mapped to relative objects derived from the XmlNode class. Theprocess that builds the XML DOM triggers when you call the Load method. You can usea variety of sources to indicate the XML document to work on, including disk files andURLs and also streams and text readers.Loading XML DocumentsThe Load method always transforms the data source into an XmlTextReader object andpasses it down to an internal loader object, as shown here:public virtual void Load(Stream);public virtual void Load(string);public virtual void Load(TextReader);public virtual void Load(XmlReader);The loader is responsible for reading all the nodes in the document and does thatthrough a nonvalidating reader. After a node has been read, it is analyzed and thecorresponding XmlNode object created and added to the document tree. The entireprocess is illustrated in Figure 5-4.Figure 5-4: The loading process of an XmlDocument object.Note that before a new XmlDocument object is loaded, the current instance of theXmlDocument object is cleared. This means that if you reuse the same instance of theXmlDocument class to load a second document, the existing contents are entirelyremoved before proceeding.182